London looks itself and other in this footage. For a 21st-century viewer it is like watching a science-fiction film in which almost everything is the same until you notice little differences that betray a completely alien quality. The past is another country, but in Claude Friese-Greene's film of the capital's streets and sights it is a place disguised as our own.

This is because this 1926 footage, which is currently a Twitter talking point, was shot in colour. Friese-Greene and his father William pioneered their own method of shooting in colour, back during the silent era: it is a byway of cinema history, an experiment that never caught on. In fact, it is part of a lost history of rival technologies in which Britain was an early leader – the Friese-Greenes fought a legal battle in the House of Lords with the rival Kinemacolor method before both were eclipsed by the American success story of Technicolor.

So there's this haunting little film, in which Claude Friese-Greene demonstrates his colour method by revealing the green embankment, the brown Thames, the dark stones of the Tower, the blue of a policeman's uniform as he directs traffic.

It's easy to see why this clip from Friese-Greene's documentary The Open Road has become an online hit. It mirrors our nostalgia perfectly, in this age of revitalised royalism and Ukip-ish invocations of England's lost green and pleasant land. Here is an uncanny full-colour glimpse of a time when even London looked innocent.

The policeman directing traffic is a case in point. There is plenty of traffic on the roads – carts and drays as well as motor vehicles – but it all stops timidly when a London Bobby raises his hand. People cross the road under his protective eye, then he lets the traffic move forward.

On the pavements, people walk by in small quiet groups. Even crowds filmed at Petticoat Lane market are properly dressed, in brown suits and hats, and mill with what can only be called gentleness.

Another friendly policeman appears patrolling the Embankment in a scene that is captioned as a "romantic" view of London. Beyond him the Houses of Parliament glow in sunlight, in a vision of an orderly, humble, relaxed Britain.

Of course it is an illusion. The film was made to show in European cinemas and gives a tourist view of the great city. In reality, there were tanks on the streets of the capital during the 1926 General Strike.

But we are all tourists in our past, a place that gets sweeter with distance. Eerily silent as it may be, this placid vision of London tickles fantasies of a kinder, more secure age. It is a national idyll in living colour.

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